In a vehicle seat for a vehicle occupant, a cushion pad including a foamed-resin material, such as polyurethane foam, is used as a seat cushion on which the occupant sits. For example, such a cushion pad is disclosed in JP-A-H06-133834.
The cushion pad has a sufficient thickness to be able to exert performance such as a cushion feeling related to seat comfort or durability. In particular, in a seat cushion of a full-form type which does not use a spring made of a metal wire under the cushion pad, the performance of the cushion pad itself becomes important. However, there is a case where the cushion pad is demanded to be thinner under various circumstances. For example, a battery pack which is one of power sources may be mounted below the seat cushion in a hybrid electric vehicle. For this reason, it is necessary to ensure a space for the battery pack by shortening the whole height of a seat assembly, and therefore, the cushion pad which is a part of the seat assembly is demanded to be thinner.